As Jacob said..... probably an amalgam of two pieces joined together at a point just above what appears to be a Grecian Ogee.
Typically these were rough-cut using a succession of plough planes, rebates etc to approach the profile then completed with Hollow and Round planes. It would all have been worked against an accurate template; bit of a lost art, (and no pun intended) however there is a comprehensive book on the subject by Matthew Bickford from The Lost Art Press
https://www.classichandtools.com/acatal ... l#SID=1220
It depends how many feet/yards/miles you have to produce as to how you go about it.......... but a decent engineers profile gauge will determine which radius H & Rs you need as a start........ if you buy them second hand, the H&R profile is based on a 60 degree segment of a circle; the size of the radius is usually (by convention) stamped on the end in 1/16s of an inch - e.g. a No: 6 is 3/8, a No: 10 is 5/8 etc. At the big end of the spectrum (over about and inch) they change to about 1/8 inch increments, but it varies by manufacturer, so always check the actual size with the gauge.
If you do go for it, it is absolutely essential for your sanity that the timber is absolutely straight grain and homogeneous in density; waving grain makes it much more difficult. The best thing that I found was to use reclaimed Victorian Deal that is dead straight.
Good luck, the book is a brilliant read in its own right.
PS - as an afterthought, The Wooden Plane by John Whelan has a section on identifying classic decorative forms